1. Field of the Invention
This invention relates to a method for making a probe card, more particularly to a method involving forming a conductive protective coating on tips of probe needles.
2. Description of the Related Art
FIG. 1 illustrates a conventional probe card 1 that usually includes a printed circuit board 11, a mounting seat 12 provided on the printed circuit board 11, and a plurality of probe needles 13 mounted on the mounting seat 12 and welded to the printed circuit board 11. In operation, the probe needles 13 made of a conductive material contact a surface of a wafer 14 for testing functionality of integrated circuits of the wafer 14. However, particles and contaminants resulting from processing of the wafer 14 may attach to the probe needles 13, which results in damage to the probe needles 13 after a period of use. A protective coating formed on the probe needles 13 has been proposed for protection of the probe needles 13.
Taiwanese patent no. 275801 discloses a method for forming the protective coating on the probe needles mounted on the printed circuit card of a probe card. In the method, a shield is required to cover portions of the probe card, including the printed circuit board, the mounting seat, and portions of the probe needles, to expose solely the tips of the probe needles on which the protective coating is to be formed. However, the covering operation is expensive and inefficient.